Heat exchangers are typically used in vehicles for transferring surplus heat from power train coolants and lubricants to the ambient air, and controlling the temperature of ambient air admitted to passenger or freight compartments of vehicles.
Thermoplastic polyamides, including nylon 6, nylon 6,6 and various high temperature nylons have been used to make heat exchangers. Often, panels have been shaped and pressed or adhered together to make tube panels, forming channels through which a heat exchange fluid can pass. However, it has been discovered that such tube panels are more likely to leak than assemblies of tubes themselves. However, assembling multiple tubes and sealing them into tube panels has been a labor intensive effort. More efficient and reliable methods of preparing tube sheet of thermoplastic polymers are desirable.
U.S. Pat. No. 5,469,915 to Cesaroni is directed to a tube panel heat exchanger; U.S. Pat. No. 5,501,759 to Forman is directed to the use of lasers to weld a collar around a single catheter tube, including optional use of a fiber optic around the tube; U.S. Pat. No. 4,744,505 to Calleson is directed to a method of assembling tubes in a header of a heat exchanger; U.S. Pat. No. 4,224,096 to Osborne is directed to splitting a single laser beam and applying two parts of the beam to opposite sides of a plastic article for welding; and U.S. Pat. No. 3,769,117 to Bowen et al. is directed to laser welding of plastic tubes. Moreover, U.S. Patent Application 2003029040 to Cesaroni is directed to laser bonding of heat exchanger tubes and International Patent Application WO 95/29785 to Dalzell and Jahsen is directed to laser powder injection welding of tubes to each other to close gaps between adjacent tubes. Each of these patents and patent applications can be referred to for understanding the state of the art and are each incorporated herein by reference.